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Retinal Complications of High Myopia

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Retinal Complications of High Myopia

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									                                                                                                                         VOL.12 NO.9 SEPTEMBER 2007
                        Medical Bulletin


     Retinal Complications of High Myopia
     Dr. Timothy YY Lai
     MBBS, MMedSc, MRCSEd, FCOphthHK, FHKAM(Ophthalmology)
     Associate Professor, Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong



                                                                                                                                      Dr. Timothy YY Lai

     Introduction                                                                        Laser photocoagulation is used for the treatment of eyes
                                                                                         which have developed retinal hole or break. This can be
     High myopia or pathological myopia is associated                                    performed in the majority of patients under topical
     with globe elongation and a refractive error of at least                            anaesthesia as an out-patient procedure. Several rows of
     6 diopters (D) and/or axial length of greater than 25.5                             laser are applied onto the retina to surround the retinal
     mm. 1-3 The prevalence of high myopia varies                                        defect in order to seal off the retinal break (Fig. 1). Since
     considerably in different ethnic groups and has been                                around 30% of eyes with acute RRD have been found to
     estimated to be around 10% in Asian populations.1,2                                 have lattice degeneration, prophylactic laser treatment
     Excessive axial elongation of the globe in high myopia                              can also be performed in patients with peripheral retinal
     can cause mechanical stretching and thinning of the                                 degenerations,15 especially those with a history of retinal
     choroid and retinal pigment epithelium layers,                                      detachment in the fellow eye.
     resulting in various retinal degenerative changes.4 It is
                                                                                          Figure 1. Retinal hole surrounded by fresh laser photocoagulation
     well known that individuals with high myopia have                                    marks in a patient with high myopia
     increased risks of retinal complications such as
     peripheral retinal degenerations, retinal tears, retinal
     detachment, posterior staphyloma, chorioretinal
     atrophy, retinal pigment epithelial atrophy, lacquer
     cracks, choroidal neovascularisation (CNV) and
     macular haemorrhage. 4-6 In a cross-sectional
     community-based epidemiological study in Hong
     Kong, 56.1% and 11.3% of subjects with high myopia
     were found to have one or more peripheral retinal
     degenerative lesion or posterior pole lesion
     respectively.7 Some of these retinal lesions may be
     associated with severe irreversible visual loss and
     therefore it is important for clinicians to be aware of
     the retinal pathologies in high myopia. This review
     aims to provide an overview on some of the important
     retinal complications associated with high myopia.


     Peripheral retinal degenerations and                                                In eyes with retinal detachment, laser photocoagulation
     rhegmatogenous retinal detachment                                                   alone is insufficient to treat the condition and
                                                                                         vitreoretinal surgery is required. Surgical modalities for
     Epidemiological studies have demonstrated increased                                 RRD include pneumatic retinopexy, scleral buckling
     prevalence of peripheral retinal degenerations in                                   surgery with cryopexy, and pars plana vitrectomy with
     association with high myopia and increased axial                                    intravitreal tamponade such as gas or silicon oil. The goal
     length.4-13 Among the different types of peripheral                                 of the surgery is to identify and seal off all retinal breaks.
     retinal degenerations in high myopia, lattice                                       For patients in whom the macula is still attached, they
     degeneration is the most important peripheral retinal                               will generally have favourable visual outcome
     degeneration which can predispose to rhegmatogenous                                 postoperatively. However, for patients in which the
     retinal detachment (RRD).14 This is because retinal tears                           central of the macula i.e. the fovea is detached, the visual
     can develop at the posterior and lateral margins of the                             prognosis of the patient is more variable and some
     lattice degeneration caused by strong vitreoretinal                                 patients might develop irreversible visual loss despite
     adhesions following posterior vitreous detachment.                                  successful retinal detachment surgery. Therefore, prompt
     Symptoms of posterior vitreous detachment and retinal                               ophthalmic consultation is advised for early detection of
     break formation include sudden or gradual increase in                               retinal detachment in order to prevent irreversible visual
     the number of floaters and/or flashes. In patients with                             loss.
     RRD, they may also develop symptoms of curtain-like
     progressive visual field loss and blurring of vision.
     Dilated fundus examination should be carried out in                                 Myopic foveoschisis and macular hole
     patients with these symptoms as soon as possible to
     detect for the development of retinal break or retinal                              Due to excessive axial elongation of the globe in high
     detachment.                                                                         myopia, patients can develop posterior bulging or ectasia

18
VOL.12 NO.9 SEPTEMBER 2007
VOL.11 NO.5 MAY 2006
                                                                                 Medical Bulletin
of the globe known as posterior staphyloma. Recent            considered to avoid gradual visual deterioration. This
advancement in retinal imaging technology using optical       is particularly important for patients with poor
coherence tomography (OCT) has demonstrated that              prognostic factors like older age of onset, larger CNV
highly myopic patients with posterior staphyloma are          and worse visual acuity at initial presentation.
predisposed to develop macular pathologies such as
myopic foveoschisis and macular hole. Myopic                  Direct thermal laser photocoagulation of myopic CNV
foveoschisis is the splitting of the retinal layers in the    has been attempted for treatment but this will lead to
macula and can result in metamorphopsia and blurring          considerable visual loss due to expansion of the laser
of vision. 16 Macular surgery may be performed in             scar in the long term and therefore thermal laser
myopic foveoschisis to prevent further deterioration of       treatment is no longer performed for myopic CNV.
vision.17,18 In more advanced stage, myopic macular hole      Other treatment modalities such as submacular surgery
can develop which may be associated with retinal              and macular translocation surgery for myopic CNV
detachment and patients will suffer from severe visual        have also been performed with some success but the
loss with reduced visual acuity. Various surgical             procedures are technically demanding and are
procedures have been performed for macular hole with          potentially associated with high CNV recurrence
or without retinal detachment and they include pars           rate. 31,32 The most commonly used method in the
plana vitrectomy with gas or silicone oil tamponade,          treatment of myopic CNV currently is photodynamic
macular buckling, and scleral shortening surgeries.19-21      therapy (PDT) with verteporfin. It is a two-steps
However, despite these interventions, reopening of the        procedure involving infusion and activation of a
macular hole and retinal redetachment may still develop       photosensitising drug. The selectivity and efficacy of
and some patients will require multiple surgeries to          PDT on the abnormal CNV are caused by differential
achieve attachment due to the loss of chorioretinal tissue    clearance of the photosensitising drug within the blood
and retinal pigment epithelial atrophy.                       stream and preferential binding to low-density
                                                              lipoprotein receptors on CNV endothelial cells. 33
                                                              Studies have shown that PDT with verteporfin can
Lacquer cracks                                                result in stabilisation of vision following treatment.34-36
                                                              However, only around 20-30% of patients will have
Lacquer cracks are formed by spontaneous ruptures in          improvement in vision after PDT with verteporfin.
the Bruch's membrane and small haemorrhages may               Combined PDT with intravitreal triamcinolone
develop within the lacquer cracks. Lacquer cracks             acetonide has also been attempted to further improve
predispose patients with high myopia to have sudden           the outcome of PDT for myopic CNV but no significant
visual loss as macular CNV may develop in close               difference was observed compared with eyes which had
proximity to the lacquer cracks. Small ingrowth of            PDT monotherapy.37
fibrovascular tissue may also give rise to small elevated
pigmented circular lesions and are known as Fuchs'            More recently, the use of angiogenesis therapy with
spots.22                                                      anti-vascular endothelial growth factor (VEGF) agents
                                                              like intravitreal bevacizumab has demonstrated
                                                              encouraging results in the treatment of myopic CNV as
Choroidal neovascularisation in high                          patients had visual gain after treatment.38,39 In a recent
                                                              study by Chan et al, 38 three monthly injections of
myopia                                                        bevacizumab resulted in a mean improvement of 2.6
                                                              lines at 6 months with 68% of patients having visual
Among various lesions associated with high myopia,            improvement of two or more lines. With the increasing
macular CNV is one of the most vision threatening             availability of other anti-VEGF agents like ranibizumab,
complications(Fig. 2).23 It develops in around 5 to 10% of    targeted angiogenesis therapy will play an increasing
eyes with high myopia and is the commonest cause of           role in the management of myopic CNV and may
CNV in young individuals and accounts for around 60%          become the treatment of choice for myopic CNV in the
of CNV in young patients aged 50 years or younger.24-26       near future.
The incidence of myopic CNV in patients with pre-
existing myopic CNV in the fellow eye is even higher, as       Figure 2. Macular haemorrhage (white arrow) associated with
more than 30% of patients will develop CNV in the              choroidal neovascularisation in high myopia
second eye within eight years after the first eye.26

Patients with new onset myopic CNV may develop
metamorphopsia, central or paracentral scotoma and
reduction in visual acuity. On clinical examination,
myopic CNV appears as a flat, small, greyish subretinal
membrane beneath or in close proximity to the fovea.
Fluorescein angiography (FA) is used to document
fluorescein leakage in the CNV and to assess the location
of the CNV for treatment planning.

The natural history of myopic CNV is generally poor
and a large proportion of patients may have visual
acuity of 20/200 or less after five years. 27,28 Poor
prognostic factors for patients with myopic CNV include
age of greater than 40 years, larger CNV, and worse
initial visual acuity.29,30 Based on studies on the natural
history of myopic CNV, active interventions should be

                                                                                                                             19
                                                                                                                         VOL.12 NO.9 SEPTEMBER 2007
                        Medical Bulletin

     Conclusions                                                                     18.Kwok AK, Lai TY, Yip WW. Vitrectomy and gas tamponade without
                                                                                        internal limiting membrane peeling for myopic foveoschisis. Br J
                                                                                        Ophthalmol 2005;89:1180-3.
     Individuals with high myopia are subject to various                             19.Ripandelli G, Coppe AM, Fedeli R, et al. Evaluation of primary surgical
     retinal pathologies including peripheral retinal                                   procedures for retinal detachment with macular hole in highly myopic
                                                                                        eyes: a randomized comparison of vitrectomy versus posterior episcleral
     degenerations, retinal detachment, and posterior pole                              buckling surgery. Ophthalmology 2001;108:2258-64.
     chorioretinal lesions. Since these retinal pathologies                          20.Kwok AK. Lai TY. Internal limiting membrane removal in macular hole
                                                                                        surgery for severely myopic eyes: a case-control study. Br J Ophthalmol
     might be associated with serious sight-threatening                                 2003;87:885-889.
     complications, patients with high myopia should be                              21.Cheung BT, Lai YY, Yuen CY, et al. Results of high-density silicone oil as
     educated about the symptoms of retinal complications                               a tamponade agent in macular hole retinal detachment in patients with
                                                                                        high myopia. Br J Ophthalmol 2007;91:719-721.
     such as retinal detachment, macular hole, and myopic                            22.Gass JDM. Myopic choroidal degeneration. In: Gass JDM, ed. Stereoscopic
     CNV. Patients should be advised to seek medical care                               atlas of macular diseases. 3rd ed. St Louis: Mosby, 1997:110-3.
                                                                                     23.Avila MP, Weiter JJ, Jalkh AE, et al. Natural history of choroidal
     promptly should such symptoms arise. Prompt referral                               neovascularization in degenerative myopia. Ophthalmology 1984;91:1573-81.
     to ophthalmologists will be useful in preventing severe                         24.Grossniklaus HE, Green WR. Pathologic findings in pathologic myopia.
     visual loss as effective surgical and medical treatments                           Retina 1992;12:127-33.
                                                                                     25.Cohen SY, Laroche A, Leguen Y, et al. Etiology of choroidal
     are available for these retinal complications especially in                        neovascularization in young patients. Ophthalmology 1996;103:1241-44.
     the early stages.                                                               26.Ohno-Matsui K, Yoshida T, Futagami S, et al. Patchy atrophy and lacquer
                                                                                        cracks predispose to the development of choroidal neovascularization in
                                                                                        pathologic myopia. Br J Ophthalmol 2003;87:570-3.
                                                                                     27.Secretan M, Kuhn D, Soubrane G, et al. Long-term visual outcome of
      References                                                                        choroidal neovascularization in pathologic myopia: natural history and
     1. Sperduto RD, Seigel D, Roberts J, Rowland M. Prevalence of myopia in the        laser treatment. Eur J Ophthalmol 1997;7:307-16.
        United States. Arch Ophthalmol.1983;101:405-7.                               28.Tabandeh H, Flynn HW Jr, Scott IU, et al. Visual acuity outcomes of
     2. Wu HM, Seet B, Yap EP, et al. Does education explain ethnic differences in      patients 50 years of age and older with high myopia and untreated
        myopia prevalence? A population-based study of young adult males in             choroidal neovascularization. Ophthalmology 1999;106:2063-7.
        Singapore. Optom Vis Sci. 2001;78:234-9.                                     29.Hayashi K, Ohno-Matsui, Yoshida T. Characteristics of patients with a
     3. Grossniklaus HE, Green WR. Pathological Findings in Pathologic Myopia.          favorable natural course of myopic choroidal neovascularization. Graefes
        Retina. 1992;12:127-33.                                                         Arch Clin Exp Ophthalmol 2004 Jul 28 [Epub head of print]
     4. Pierro L, Camesasca FI, Mischi M, Brancato R. Peripheral retinal changes        doi:10.1007/s00417-004-0968-5.
        and axial myopia. Retina. 1992;12:12-7.                                      30.Kojima A, Ohno-Matsui K, Teramukai S, et al. Factors associated with the
     5. Celorio JM, Pruett RC. Prevalence of Lattice Degeneration and Its Relation      development of chorioretinal atrophy around choroidal
        to Axial Length in Severe Myopia. Am J Ophthalmol. 1991;111:20-3.               neovascularization in pathologic myopia. Graefes Arch Clin Exp Ophthalmol
     6. Hyams SW, Neumann E. Peripheral retinal in myopia. With particular              2004;242:114-9.
        reference to retina breaks. Br J Ophthalmol 1969;53,300-6.                   31.Uemura A, Thomas MA. Subretinal surgery for choroidal
     7. Lai TYY, Fan DSP, Lai WWK, Lam DSC. Peripheral and posterior pole               neovascularization in patients with high myopia. Arch Ophthalmol
        retinal lesions in association with high myopia: a cross-sectional              2000;118:344-50.
        community-based study in Hong Kong. Eye 2006 Sep 1 [Epub ahead of            32.Hamelin N, Glacet-Bernard A, Brindeau C, et al. Surgical treatment of
        print].                                                                         subfoveal neovascularization in myopia: macular translocation vs surgical
     8. Curtin BJ, Karlin DB. Axial length measurements and fundus changes of           removal. Am J Ophthalmol 2002;133:530-6.
        the myopic eye. I. The posterior fundus. Trans Am Ophthalmol Soc             33.Flower RW. Expanded hypothesis on the mechanism of photodynamic
        1970;68:312-34.                                                                 therapy action on choroidal neovascularization. Retina 1999;19:365-69.
     9. Karlin DB, Curtin BJ. Peripheral chorioretinal lesions and axial length of   34.Blinder KJ, Blumenkranz MS, Bressler NM, et al. Verteporfin therapy of
        the myopic eye. Am J Ophthalmol 1976;81,625-35.                                 subfoveal choroidal neovascularization in pathologic myopia: 2-year
     10.The Eye Disease Case-Control Study Group. Risk factors for idiopathic           results of a randomized clinical trial-VIP report no. 3. Ophthalmology
        rhegmatogenous retinal detachment. Am J Epidemiol 1993;137:749-57.              2003;110:667-73.
     11.Yura T. The relationship between the types of axial elongation and the       35.Montero JA, Ruiz-Moreno JM. Verteporfin photodynamic therapy in
        prevalence of lattice degeneration of the retina. Acta Ophthalmol Scand         highly myopic subfoveal choroidal neovascularisation. Br J Ophthalmol
        1998;76:90-5.                                                                   2003;87:173-6.
     12.Gozum N, Cakir M, Gucukoglu A, Sezen F. Relationship between retinal         36.Lam DS, Chan WM, Liu DT, et al. Photodynamic therapy with
        lesions and axial length, age and sex in high myopia. Eur J Ophthalmol.         verteporfin for subfoveal choroidal neovascularization of pathologic
        1997 Jul-Sep;7(3):277-82                                                        myopia in Chinese eyes- a prospective series of one and two years follow-
     13.Saw SM, Gazzard G, Shih-Yen EC, Chua WH. Myopia and associated                  up. Br J Ophthalmol 2004;88:1315-9.
        pathologic complications. Ophthalmic Physiol Opt 2005;25:381-91.             37.Chan WM, Lai TY, Wong AL, et al. Combined photodynamic therapy and
     14.Lewis H. Peripheral retinal degenerations and the risk of retinal               intravitreal triamcinolone injection for the treatment of choroidal
        detachment. Am J Ophthalmol 2003;136:155-160.                                   neovascularization secondary to pathological myopia: a pilot study. Br J
     15.Hyams SW, Meir E, Ivry M, et al. Chorioretinal lesions predispoed into          Ophthalmol 2007;91:174-179.
        retinal detachments. Am J Ophthalmol 1974;78:420-429.                        38.Chan WM, Lai TY, Liu DT, Lam DS. Intravitreal bevacizumab (Avastin)
     16.Takano M, Kishi S. Foveal retinoschisis and retinal detachment in severely      for myopic choroidal neovascularization: 6-month results of a prospective
        myopic eyes with posterior staphyloma. Am J Ophthalmol 1999;128:472-476.        pilot study. Ophthalmology 2007 June 26[Epub ahead of print]
     17.Ikuno Y, Sayanagi K, Ohji M, et al. Vitrectomy and internal limiting         39.Yamamoto I, Rogers AH, Reichel E, et al. Intravitreal bevacizumab
        membrane peeling for myopic foveoschisis. Am J Ophthalmol                       (Avastin) as treatment for subfoveal choroidal neovascularization
        2004;137:719-724.                                                               secondary to pathological myopia. Br J Ophtahlmol 2007;91:157-160.




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